Strain relieving device



A. a CALDWELL 2.225,031

' STRAIN anunvme nnvxcm xned July 29, 1931 141.5537- .5; Civic WELL.

Patented' Dec. 17. 1040 s'rasm narmvmo'nnvrcs Albert E.Caldwell, Galesburg, Ill. Application July 29, 1937, Serial No. 156,290

4 Claims.

The present invention relres in general to a strain relieving device, and is more particularly concerned with an improved arrangement for relieving the strain on electrical conductors at terminal connections. 1 i

In connections with electrical fittings, such as plugs, fixtures, electrical devices, etc.,. it is the usual practice to providepelectrical conductors which are connectedby suitable screws or other means to a terminal connection. Quite frequent- 1y these conductors are subjected. to pulling stresses, and it will be evident that under certain conditions the stresses will be carried directly to the terminal screws. As a result, unsatisfactory 1! operation frequently fol1ows,,due to the conductors becoming broken, the screws atthe terminal becoming loosenedso that a proper connection is notmade, and the like.-

Appreciating the objections and difilculties en countered in the present day arrangements this invention contemplates an improved stress reliev ing device whichjmay be easily and removably attached to the conductor insulation, and which will cooperate with a stationary or relatively fixed l6 memberv at theterminal' connection so as to relieve any strain being transmitted to the terminals due-to pulling stresses applied to the con- .ductors. I

A further object-of the invention is to provide scan improved device of --the.chara cter described which is of simple construction, may easily and readily be attached or detached to a conductor, and which may be'manufactured atfa relatively low cost. i r A further object is-to provide an improved electrical connector embodying the features ofthe present invention. 1:

Other objects and features of the invention will more fully appear from the following detailed 4) description, taken in connection with the accompanying drawing, which illustrates a single embodiment thereof, and in which:

Figure 1 is a view, partially in section, showing the device of the present invention applied to I a connection plug;

Figure 2 is an enlarged view of the device as seen from one side;

Figure 3 is a similar view of the device as seen so from the opposite side;

Figure 4 is a sectional view through the same, showing the-cooperative relationship of its parts, taken substantially on the line IV-IV of F18- Y ure 3;

. Figure 5 is a fragmentary view showing the v As shown on the drawing:

position of the parts of the device, when' the deviceis initially applied to a conductor; and

Figure 6 is a similar view, showing the parts positioned to secure the device to the conductor.

For purposes of illustration, the present in-' vention is disclosed in Figure 1 as being utilized in connection with a plug connector as generally indicated at lll. Although this particular application of thedevice is shown, it will be read- 0 ily apparent to one skilled-in the art that the device has many uses and is not to be limited to the above mentioned single application.

In general, the plug. embodies the usualarrangement of parts comprising a body portion 15 v 'l I of hollow construction to form an insulating" shell for preventing contact with the live parts therein. The body portion ll has its bottom pro- ,vided' with ,acentral opening I! for receiving an .Jend'of an electric conductor it which in this ingo tance'comprises a pair of conductors within a single insulating sheath or covering. The conductors are respectively connected to a pair of insulatingly spaced" contact elements l4 and I5 which, are suitably mounted on the shell body. as

The conductors may be connected in any desired manner to the contact elements, and are shown as being connected by means of a terminal screw IS in each case;

The arrangement so far described is the usual 80 construction, andlt will be evident that during the'useofthe'plug, as when-removing it from a receptacle,- theusualprocedure would be to pull on'the conductor rather than to grasp the plug body.- As a consequence, the pulling stresses in as the conductor are carried directly to the terminal connections of the conductors. Due. to stressing the conductors'at their points of connection to the terminals, the conductors become broken and the terminal screws loosened, whereby a defective 0 electrical connection results.

In order to overcome this difilculty and pro vide means for relieving strain on the terminal connection of the conductor, when pulling stresses are applied to the conductor, the present invention proposes to provide a device which will form an abutment with the plug body and hold the conductor against movement in the direction in which the conductor is pulled. More specifically, the device comprises a pair of ciro cular disk members l1 and II which are secured in surface engagement by means of an open-ended ring member I! of substantially channel-shape. The open side of the channel is disposed inwardly to form a groove for receiving-the peripheral v at edges of the disk members I! and I8. The member l 8 is preferably constructed of metal, whereas the disk members supported therein are preferably of any fiber.

The disk members I! and I8, as shown clearly in Figures 2 and 3 are provided with substantially U-shaped cut-outs 20 and 2i, respectively, the latter being provided with a toothed edge as shown at 22. Since the disk members may be relatively rotated, it will be evident that they may be easily disposed in position to bring the cut-out portions into coincidence or one of the members may be rotated relative to the other so as to bring the cut-out portions into angularly disposed relationship and form, in eifect, a closed opening substantially at the center of the disks and supporting ring member l9.

With the cutout portions coincidental, a conductor may be laterally inserted thereinto. By rotating the disk I! and ring member I! as a unit, the ring and disk I! being secured against relative movement by a deflected edge 23 of one side of the channel, the conductor will be enclosed by the cooperative action of the two disks and secured against removal from the device, as shown in Figure 6. The teeth 22, when the device is attached to the conductor, are forced against the conductor insulation thus holding the device against movement axially of the conductor.

In using the device with a plug connector, the body II is preferably provided with a, socket portion 24 in axial alignment with the opening I 2 in the bottom of the plug body, the socket portion 24 being of slightly larger bore than the opening I2 so as to define an abutment shoulder 25, against which the device embodying the features of the present invention may abut, the device being secured to the connection end of the conductor.

From the foregoing description, it will be apparent that the present invention provides an improved device for use in terminal connections 01 a conductor, whereby pulling stresses on the conductor are prevented from being transmitted to the terminal securing means; a device which may be readily attached to and detached from the conductor; which maybe manufactured at a relatively small cost; and which may be utilized to produce an improved electrical connector embodying the features of the invention.

It is, of course, to be understood that although I have described in detail a single embodiment of the invention, the invention is not to be thus limited, but only insofar as defined by the scope and spirit of the appended claims.

I claim as my invention:

1. A strain relieving device for application to a cord comprising a pair of disks in superposed suitable insulating material, such as relation, each of said disks having an openended slot therein, a split ring member having spaced ends and of channel shaped section, said disks having their peripheral edges disposed in said channel, and means for securing one of said disks to said ring member with the open end of its slot between the spaced ends of said ring, the other disk being rotatively mounted in respect to said ring member whereby it may be rotated to bring the disk slots into and out 01 registration. a

2 A strain relieving device for application to a cord comprising a pair or disks in superposed relation, each of said disks having an openended slot therein, a split ring member having spaced ends and of channel shaped section,said disks having their peripheral edges disposed in said channel, means for securing .one of said disks to said ring member with the open end of its slot between the spaced ends of said ring, the other disk being rotatively mounted in respect to said ring member whereby it may be rotated to bring the disk slots into and out of registration, and serrations in at least one of the disk slots for engaging said cord.

3. A strain relieving device for'application to a cord comprising a pair 01' disks in superposed relatively rotative coaxial relation, each of said disks having an open-ended slot therein, the slots being substantially coincident in one adjusted relative position of the disks, and a memberhaving a peripheral recess to receive a cord and forming an arcuate channel for receiving the peripheral edges of said disks therein with one of said disks in guided retained rotative relation,'said channel member having portions extending lengthwise from one side past diametrically disposed points of said disks and retaining them against bodily lateral disengagement, but enabling relative rotative movements thereof.

4. A strain relieving device for application to a cord comprising a pair of disks in superposed relatively rotative coaxialrelation, each of said disks having an open-ended slot therein, the

slots being substantially coincident in one adjusted relative position oifthe disks, a channel forming member having a peripheral recess to receive a cord and having the peripheral edges of the disks disposed therein, one otthe disks being secured against rotative channel and the other being free for relative rotative movement in the channel, whereby the disks may be disposed in their said superposed relation with their slots relatively in and out oi registration, and serrations in the slot of the freely movable disk for grippingly retaining it against rotative movement when the device is applied to the cord.

ALBERT E. CALDWELL.

movement in the 

